The present disclosure is directed to polycarbonate compositions, manufacture of the compositions, articles containing the compositions, and methods of manufacture of the articles.
Polycarbonates are useful in a wide variety of applications at least in part because of their good balance of properties, such as moldability, heat resistance and impact properties among others. However, standards for flame spread, heat release, and smoke generation upon burning have become increasingly stringent, particularly in applications used in mass transportation (aircraft, trains, and ships), as well as building and construction. For example, the European Union has approved the introduction of a new harmonized fire standard for rail applications, namely EN-45545, to replace all currently active different standards in each member state. This standard will impose stringent requirements on flame spread, heat release and smoke density properties allowed for materials used in these applications.
One difficulty in developing materials that meet the stringent standards is that use of one component to improve one property, for example, flame retardance, can concomitantly degrade another selected property, such as smoke density. Accordingly, there remains a need in the art for polycarbonate compositions that have excellent flame spread, heat release, and smoke properties at the same time. It would be a further advantage if the compositions could be rendered flame retardant, low heat release and low smoke without a significant detrimental effect on one or more of material cost, processability, and mechanical properties.